Optical scattering filter

Claim 2

An optical filter having relatively high transmission to infrared radiation comprising: a thin transmitting wafer comprising a microporous material producing selective scattering of all wavelengths shorter than a selected wavelength, said wafer (i) having a relatively sharp cut-on front, (ii) being substantially opaque to radiation of wavelengths shorter than said selected wavelength and (iii) being highly transmissive to radiation of wavelengths longer than said cut-on front; and at least one absorbing material having an absorption band in the shorter wavelength transmission region of said wafer, said material absorbing at least a portion of the energy transmitted by said wafer.

Claim 3

An optical filter having relatively high transmission to infrared radiation comprising: a thin transmitting wafer comprising a microporous material producing selective scattering of all wavelengths shorter than a selected wavelength; and at least one absorbing material having an absorption band in the shorter wavelength transmission region of said wafer, said material absorbing at least a portion of the energy transmitted by said wafer.

Claim 4

An optical filter having relatively high transmission to infrared radiation comprising: a thin transmitting wafer comprising a microporous material producing selective scattering of all wavelengths shorter than a selected wavelength; and at least one absorbing material having an absorption band in the shorter wavelength transmission region of said wafer, said material absorbing at least a portion of the energy transmitted by said wafer.

Claim 5

An optical filter having relatively high transmission to infrared radiation comprising: a polyethylene matrix having micron size pores of substantially uniform diameter substantially evenly distributed therethrough, said matrix being substantially opaque to all wavelengths shorter than a first wavelength; and at least one material having an absorption band in the shorter wavelength transmission region of said matrix and absorbing at least a portion of the energy transmitted by said matrix.

Claim 6

An optical filter having relatively high transmission to infrared radiation comprising: a polyethylene matrix having micron size pores of substantially uniform diameter substantially evenly distributed therethrough, said matrix being substantially opaque to all wavelengths shorter than a first wavelength; and at least one material having an absorption band in the shorter wavelength transmission region of said matrix and absorbing at least a portion of the energy transmitted by said matrix.

Claim 7

An optical filter having relatively high transmission to infrared radiation comprising: a polyethylene matrix having substantially evenly distributed pores therein of substantially uniform diameters, said matrix being substantially opaque to radiation of wavelengths shorter than a first wavelength and having a relatively sharp cut-on front and being highly transmissive to radiation of wavelengths longer than said cut-on front; and a plurality of absorbing materials having overlapping absorption bands of such intensity that the region from a second wavelength to a third wavelength is substantially opaque, said second wavelength being shorter than said first wavelength and said third wavelength being longer than said first wavelength such that said filter is substantially opaque to radiation of wavelengths shorter than said third wavelength, said materials positioned to absorb radiation between said second and third wavelengths.

Claim 8

An optical filter having relatively high transmission to infrared radiation comprising: a polyethylene matrix having substantially evenly distributed pores therein of substantially uniform diameters, said matrix being substantially opaque to radiation of wavelengths shorter than a first wavelength and having a relatively sharp cut-on front and being highly transmissive to radiation of wavelengths longer than said cut-on front; and a plurality of absorbing materials having overlapping absorption bands of such intensity that the region from a second wavelength to a third wavelength is substantially opaque, said second wavelength being shorter than said first wavelength and said third wavelength being longer than said first wavelength such that said filter is substantially opaque to radiation of wavelengths shorter than said third wavelength, said materials positioned to absorb radiation between said second and third wavelengths.

Claim 9

An optical filter having relatively high transmission to infrared radiation comprising the combination of: a first matrix of polyethylene having micron size pores of substantially uniform diameter suBstantially evenly distributed therethrough, said matrix being substantially opaque to radiation of wavelengths shorter than a first wavelength; having a relatively sharp cut-on front and being highly transmissive to radiation longer than said cut-on front; and at least a second matrix having at least one finely divided material evenly distributed therethrough, said finely divided material having an absorption band that is substantially opaque between a first and second wavelength, said second wavelength being shorter than said first wavelength and said third wavelength being longer than said first wavelength, said second matrix having no significant absorption bands in the region from said third wavelength to at least 300 microns.

Claim 10

An optical filter having relatively high transmission to infrared radiation comprising the combination of: a first matrix of polyethylene having micron size pores of substantially uniform diameter suBstantially evenly distributed therethrough, said matrix being substantially opaque to radiation of wavelengths shorter than a first wavelength; having a relatively sharp cut-on front and being highly transmissive to radiation longer than said cut-on front; and at least a second matrix having at least one finely divided material evenly distributed therethrough, said finely divided material having an absorption band that is substantially opaque between a first and second wavelength, said second wavelength being shorter than said first wavelength and said third wavelength being longer than said first wavelength, said second matrix having no significant absorption bands in the region from said third wavelength to at least 300 microns.

Claim 11

An optical filter having relatively high transmission to infrared radiation comprising: a polyethylene matrix having micron size pores of substantially uniform diameter substantially evenly dispersed therethrough; at least a second matrix; and a plurality of absorbing materials having overlapping absorption bands of intensity such that the region between a second wavelength and a third wavelength is substantially opaque, said second wavelength being shorter than said first wavelength and said third wavelength being longer than said first wavelength, each of said plurality of absorbing materials being finely divided and substantially evenly dispersed throughout said second matrix, said second matrix having no significant absorption bands in the region from said third wavelength to at least 300 microns.

Claim 12

An optical filter having relatively high transmission to infrared radiation comprising: a polyethylene matrix having micron size pores of substantially uniform diameter substantially evenly dispersed therethrough; at least a second matrix; and a plurality of absorbing materials having overlapping absorption bands of intensity such that the region between a second wavelength and a third wavelength is substantially opaque, said second wavelength being shorter than said first wavelength and said third wavelength being longer than said first wavelength, each of said plurality of absorbing materials being finely divided and substantially evenly dispersed throughout said second matrix, said second matrix having no significant absorption bands in the region from said third wavelength to at least 300 microns.

Claim 13

An optical filter having relatively high transmission to infrared radiation and a cut-on wavelength in the region from approximately 14 to 150 microns comprising: a matrix having micron size pores of substantially uniform diameter substantially evenly distributed therethrough for scattering radiation of wavelengths shorter than a preselected wavelength and transmitting radiation longer than said preselected wavelength; and at least one material having an absorption band in the region of wavelengths longer than said preselected wavelength selected from the group BaCO3, BaF2, BeO, CaCO3, Li2CO3, LiF, SrF2, TiO2 and freshly smoked MgO, said material positioned to absorb radiation in the region of wavelengths longer than said preselected wavelength.

Claim 14

An optical filter having relatively high transmission to infrared radiation and a cut-on wavelength in the region from approximately 14 to 150 microns comprising: a matrix having micron size pores of substantially uniform diameter substantially evenly distributed therethrough for scattering radiation of wavelengths shorter than a preselected wavelength and transmitting radiation longer than said preselected wavelength; and at least one material having an absorption band in the region of wavelengths longer than said preselected wavelength selected from the group BaCO3, BaF2, BeO, CaCO3, Li2CO3, LiF, SrF2, TiO2 and freshly smoked MgO, said material positioned to absorb radiation in the region of wavelengths longer than said preselected wavelength.

Claim 15

An optical filter having relatively high transmission to infrared radiation and a cut-on wavelength in the region from approximately 14 to 150 microns comprising: a matrix having micron size pores of substantially uniform diameter substantially evenly distributed therethrough for scattering wavelengths shorter than a preselected wavelength and transmitting radiation longer than said preselected wavelength; and a plurality of absorbing materials having absorption bands in the region of wavelengths longer than said preselected wavelength, said materials being substantially evenly distributed throughout a matrix, at least one of said materials selected from the group BaCO3, BaF2, BeO, CaCO3, Li2CO3, LiF, SrF2, TiO2 and freshly smoked MgO, said materials positioned to absorb radiation in the region of wavelengths longer than said preselected wavelength.

Claim 16

An optical filter having relatively high transmission to infrared radiation and a cut-on wavelength in the region from approximately 14 to 150 microns comprising: a matrix having micron size pores of substantially uniform diameter substantially evenly distributed therethrough for scattering wavelengths shorter than a preselected wavelength and transmitting radiation longer than said preselected wavelength; and a plurality of absorbing materials having absorption bands in the region of wavelengths longer than said preselected wavelength, said materials being substantially evenly distributed throughout a matrix, at least one of said materials selected from the group BaCO3, BaF2, BeO, CaCO3, Li2CO3, LiF, SrF2, TiO2 and freshly smoked MgO, said materials positioned to absorb radiation in the region of wavelengths longer than said preselected wavelength.

Claim 17

An optical filter having relatively high transmission to infrared radiation and a cut-on wavelength in the region below 150 microns comprising: a polyethylene matrix having micron size pores of substantially uniform diameter substantially evenly dispersed therethrough, said matrix being substantially opaque to all wavelengths shorter than a first wavelength in the regions from approximately 14 to 35 microns; and at least one material having an absorption band in the region of wavelengths longer than said first wavelength selected from the group BaCO3, BaF2, BeO, CaCO3, Li2CO3, LiF, SrF2, TiO2 and freshly smoked MgO, said material positioned to absorb radiation in the region of wavelengths longer than said first wavelength.

Claim 18

An optical filter having relatively high transmission to infrared radiation and a cut-on wavelength in the region below 150 microns comprising: a polyethylene matrix having micron size pores of substantially uniform diameter substantially evenly dispersed therethrough, said matrix being substantially opaque to all wavelengths shorter than a first wavelength in the regions from approximately 14 to 35 microns; and at least one material having an absorption band in the region of wavelengths longer than said first wavelength selected from the group BaCO3, BaF2, BeO, CaCO3, Li2CO3, LiF, SrF2, TiO2 and freshly smoked MgO, said material positioned to absorb radiation in the region of wavelengths longer than said first wavelength.

Claim 19

An optical filter having relatively high transmission to infrared radiation comprising: a thin transmitting wafer comprising a matrix having micron size pores of substantially uniform diameter substantially evenly distributed therethrough, said wafer producing selective scattering of all wavelengths shorter than a selected wavelength; and at least one non-hygroscopic absorbing material having an absorption band in the shorter wavelength transmission region of said wafer, said material absorbing at least a portion of the energy transmitted by said wafer.

Claim 20

An optical filter having relatively high transmission to infrared radiation comprising: a thin transmitting wafer comprising a matrix having micron size pores of substantially uniform diameter substantially evenly distributed therethrough, said wafer producing selective scattering of all wavelengths shorter than a selected wavelength; and at least one non-hygroscopic absorbing material having an absorption band in the shorter wavelength transmission region of said wafer, said material absorbing at least a portion of the energy transmitted by said wafer.

Claim 21

An optical filter according to claim 10 wherein said absorbing materials are substantially evenly distributed through a second thin transmitting wafer.

Claim 22

An optical filter according to claim 10 wherein said matrix is polyethylene.

Claim 23

An optical filter according to claim 8 wherein: said preselected wavelength is in the region from approximately 10 to 35 microns; and said plurality of absorbing materials have overlapping absorption bands of intensity such that the region between said preselected wavelength and about 46 microns is substantially opaque, said plurality of absorbing materials including SrF2, BeO, LiF and freshly smoked MgO, said materials positioned to absorb radiation between said preselected wavelength and about 46 microns.

Claim 24

An optical filter according to claim 13 wherein said plurality of absorbing materials include approximately 24.4 mg/in2 of SrF2, 7.3 mg/in2 of BeO, 4.1 mg/in2 of LiF, and 12.2 mg/in2 of freshly smoked MgO.

Claim 25

An optical filter according to claim 8 wherein: said preselected wavelength is in the region from approximately 10 to 35 microns; and said plurality of absorbing materials have overlapping absorption bands of intensity such that the region between said preselected wavelength and about 53 microns is substantially opaque, said plurality of absorbing materials including BaF2, SrF2, LiF, BeO, and freshly smoked MgO, said materials positioned to absorb radiation between said preselected wavelength and about 53 microns.

Claim 26

An optical filter according to claim 15 wherein: said plurality of absorbing materials include 26.9 mg/in2 of BaF2, 65 mg/in2 of SrF2, 8.2 mg/in2 LiF and BeO and 12.2 mg/in2 of freshly smoked MgO.

Claim 27

An optical filter according to claim 2 wherein: said preselected wavelength is in the region from approximately 10 to 35 microns; and said one absorbing material comprises a sufficient quantity of TiO2 evenly distributed over an area in sufficient quantity to render the region between said preselected wavelength and about 37 microns substantially opaque.

Claim 28

An optical filter according to claim 17 wherein: said quantity of TiO2 is approximately 18.3 mg/in2.

Claim 29

An optical filter according to claim 2 wherein: said preselected wavelength is in the region from approximately 10 to 20 microns; and said one absorbing material comprises a sufficient quantity of freshly smoked MgO in such concentration to render the region between said preselected wavelength and about 26 microns substantially opaque.

Claim 30

An optical filter according to claim 19 wherein: said concentration of freshly smoked MgO is approximately 30 mg/in2.

Claim 31

An optical filter according to claim 8 wherein: said preselected wavelength is in the region from approximately 10 to 20 microns; and said plurality of absorbing materials have overlapping absorption bandS of intensity such that the region between said preselected wavelength and about 26 microns is substantially opaque, said plurality of absorbing materials including BeO and freshly smoked MgO and positioned to absorb radiation between said preselected wavelength and about 26 microns.

Claim 32

An optical filter according to claim 21 wherein: said plurality of absorbing materials include 4.1 mg/in2 of BeO and 30 mg/in2 of freshly smoked MgO.